#include <stdio.h>
void one_three(void);
void two(void);
int main (void)
{
    
    printf("starting now :\n");
    one_three();
    two ();
    printf("three\n");
    printf("done!");

    return 0;
}
void one_three(void)
{
    printf("one\n");
}
void two (void)
{
    printf("two\n");/*符号！符号!符号！再强调一遍！*/
}